If the following command succeeds:
then that means your internet connection is working perfectly. It means your routing table is able to find the internet, and it also means that your DNS server is working properly.Code:ping virjacode.com
If Firefox won't display webpages for you, then the only thing I can think is that you have invalid proxy server settings in your Firefox browser. Open up Firefox and go to Tools->Options->Advanced->Network, then click on the "Settings" button.
If you ever want to set your internet connection at the command line in Linux then here's a guide:
Linux Internet Connection - Virjacode